Second-law-based analysis of vapor-compression refrigeration cycles: Analytical equations for COP and new insights into features of refrigerants

•Second-law analysis leads to analytical COP formulas for refrigeration cycles.•Relative errors of the analytical equations are smaller than ±5.0%.•The analytical expressions characterize the influence of refrigerants.•Global entropy analysis elucidates the impact of cycle processes on COP. This art...

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Bibliographic Details
Published in:Energy conversion and management 2017-04, Vol.138, p.426-434
Main Authors: Ma, Weiwu, Fang, Song, Su, Bo, Xue, Xinpei, Li, Min
Format: Article
Language:English
Subjects:
Coefficient of performance
Compression
Computer simulation
Entropy
Entropy generation analysis
Equations of state
Heat pump
Irreversible processes
Jaw
Mathematical analysis
Mathematical models
Refrigerants
Refrigeration
Second-law analysis
Thermodynamics
Throttling
Vapor compression refrigeration
Vapor-compression refrigeration cycle
Vapors
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Summary:•Second-law analysis leads to analytical COP formulas for refrigeration cycles.•Relative errors of the analytical equations are smaller than ±5.0%.•The analytical expressions characterize the influence of refrigerants.•Global entropy analysis elucidates the impact of cycle processes on COP. This article reports a second-law-based analysis of the vapor-compression refrigeration cycle, which leads to a set of explicit theoretical formulas for the coefficient of performance (COP). These analytical expressions provide a fast and accurate approach to computer simulations of the vapor-compression cycle without recourse to thermodynamic diagrams or equations of state. The second-law-based analysis yields specific expressions for the entropy generations of irreversible processes, enabling us to evaluate the thermodynamic features of the refrigerant and to elucidate the thermodynamic mechanisms behind the effects of the cycle processes, including superheat, subcooling, and throttling processes. In particular, these processes can interact, therefore this paper presents a global entropy generation analysis for evaluating the impact of the interacted processes on COP.
ISSN:0196-8904
1879-2227
DOI:10.1016/j.enconman.2017.02.017